1. Field of the Invention
This invention relates to a display control apparatus, a display control program and a display control method.
2. Description of the Related Art
CGIs (common gateway interfaces) are known as interfaces for executing a user program on a web server. A CGI is a program installed in a server that executes a process in response to a CGI request from a web browser of a client and the web browser displays the HTML output by the user program so that a user of the client who requested the execution of the process can see the results of the execution at the web server on the web browser.
A method of avoiding double transmissions from a business use HTML screen on a web browser in known (see, for example, Patent Document: Jpn. Pat. Appln. Laid-Open Publication No. 2001-229103).
However, accessing of a file where a CGI program is written itself is a CGI request. Therefore, when a web browser is updated after executing a program, a multiple processing may occur at the web server as a similar CGI request is issued to the web server.
The web server may check a CGI request and returning an error in order to avoid such multiple processing. However, the web server cannot determine if a process is a normal process or an abnormal process when one or more normal processes coexist with one or more abnormal processes in a CGI request.
Now, an example of operation error that may occur due to a CGI request when a web browser is updated will be described below by referring to FIGS. 8 and 9.
FIG. 8 is a schematic illustration of a displayed image of a web browser on a display screen for controlling On and Off of a power supply of a computer. FIG. 9 is a flowchart of an operation error that might arise in a computer control by a web browser when a user inadvertently updates the web browser. Referring to FIG. 8, assume that web browser A and web browser B that are different from each other are adapted to control On/Off of the power supply to the computer, and the power supply to the computer is On in an initial condition.
As an Off button is clicked, the web browser A issues a power supply Off request to the computer being controlled by using a Web-UI (web-user interface) output from the CGI program as shown in FIG. 8 (S101). And when an On button is clicked, the web browser B issues a power supply On request to the computer just like the browser A in a state where the power supply of the computer is turned Off (S102).
Subsequently, the web browser A issues a power supply Off request (S103) and thereafter the web browser B issues a power supply On request (S104). Then, the web browser A updates the CGI to which it issued the power supply Off request while the web browser A accesses the CGI, holding the power supply Off request in Step S103, to consequently issue a power supply Off request (S105).
With the above-described method, the computer that is controlled by the user who operates the web browsers may determine such inadvertent update as an updating for re-controlling and an operation error may occur.